1. Field of the Invention
The preset invention relates to hooks for supporting retractable roof coverings used on greenhouses. More specifically, the invention relates to such hooks which have are designed to separate the roof covering and/or any reinforcing tape material from the suspension wire and a locking means to prevent unfastening and to increase the hook's holding capacity.
2. Description of the Prior Art
In greenhouses, it is common for the roofs to be retractable and made of a fabric covering which can be pleated or folder Such roof coverings are typically made of woven polyethylene or polypropylene and are suspended, by means of hooks, from wires or rods extending along the top of the greenhouse. Normally, such hooks are connected to a reinforcing tape which is then attached to the roof fabric.
In greenhouses having such a fabric roof covering, it is common for wind to cause the roof covering material to billow or flap thereby causing that part of the covering or reinforcing tape material which is joined to the book to rub against the suspending rod or wire, which, in turn, damages such material due to abrasion. Hooks having a means of separating the fabric from the wire have been proposed but involve a complicated method of assembly or use. Further, since many of the known hooks do not have a locking means, it is also common for such hooks to be disengaged from the supporting rod or wire or for the roof covering to slip off. In addition, those hooks that do have a locking means can only be locked on site which, as discussed below, results in various disadvantages.
Various hooks have been proposed to address these individual problems; however, no one device has provided an adequate solution to both.
For example, in U.S. Pat. No. 5,761,776 (which is commonly owned with the present invention), there is described a hook having an integral separator. Although such hook achieves the stated purpose, the means for attaching the hook to the reinforcing tape of the roof covering requires manual manipulation of the pin in a plane perpendicular to that of the hook. Due to the required strength of the hook material, such manipulation is rendered difficult.
Another disadvantage with this hook is that the locking of the pin prevents both the roof covering as well as the suspension wire from being disengaged. Thus, the pin may only be locked after the hook is attached to the suspension wire thereby causing the manipulation of the pin to be more difficult since it must be done onsite and overhead. Further, the Red manipulation of such hook makes it difficult to design a machine to perform the required manipulations.
Therefore, a need exists for an improved hook for roof coverings and the like which overcomes the disadvantages of the known devices.